$ \left(\dfrac{1}{16}\right)^{-\frac{1}{2}}$
Explanation: $= 16^{\frac{1}{2}}$ To simplify $16^{\frac{1}{2}}$ , figure out what goes in the blank: $\left(? \right)^{2}=16$ To simplify $16^{\frac{1}{2}}$ , figure out what goes in the blank: $\left({4}\right)^{2}=16$ so $ 16^{\frac{1}{2}}=4$